I have a chronic problem with my 260E with the O2 light comes on and off while I am driving all the time. I have replaced the O2 sensor, fuel injectors cleaned, fuel filter replace, major tune up, replace air flow meter and drained the fuel tank to ensure no water contaminates.
I currently has the car in a repair shop and the mechanic thinks that the KU Control Unit is bad referance part number 0055458032. I recently was told that the Mass Control Unit Part Number 011-545-79-32 was bad. Do you have any suggestions? These repairs and parts are getting very expensive to replace. Awaiting replies!

Here are my symptoms:
Oxygen sensor light flashing on and off accompanied by the engine stalling and losing power but not completely dying. This happens at all RPM's, at all different loads, hot and cold but mainly hot.

Computer replaced 3 months ago (with used). New oxygen sensor 3 months ago. New overvoltage relay 3 months ago. New cap, rotor, and wires 2 months ago. New tires, brakes and rotors all the way around - not that it should help.

New oxygen sensor within the last 3 days, computer swapped out during diagnosis - no change. Wiring harness inspected - looked good.

Shop has tried the temperature sensor but now thinks it could be the computer again.

I replaced the Jettronic Computer and it solve my problems. This unit is located behind the battery on the firewall. You may want to get your Air Flow Meter checked out before you replace another computer. I had multi problems with my car but I had to work through them all. Good Luck.